The present invention relates to a multi-cylinder swash plate compressor and, more particularly, to an apparatus capable of controlling such a compressor into a part-capacity operation mode, as distinguished from the usual full-capacity operation mode.
In a swash plate compressor with multiple cylinders, it is desirable, and possible, to render some of the cylinders ineffective to lower the compression capacity or output pressure in response to a decrease in load. A swash plate compressor usually includes low pressure and high pressure chambers for temporary storage of a gas which are formed in each of front and rear covers mounted on a cylinder block. It will therefore be easy to arrange the compressor such that a compressed gas discharged into the high pressure chamber in one of the covers is fed back into the lower pressure chamber, thereby halving the entire capacity of the compressor. However, since the high pressure chambers in both the front and rear covers are connected to a common delivery conduit and to each other, the gas from the high pressure chamber in one cover tends to be communicated back to the low pressure chamber of the other cover during a part-capacity operation mode of the compressor. An implement heretofore known for coping with such a tendency comprises a check valve which is located in the delivery passageway between the high pressure chambers in the opposite covers. The check valve prevents the high pressure gas from flowing in the reverse direction while the compressor is operated in the part-capacity mode. This is not acceptable because, in a full-capacity operation mode, the check valve creates resistance to the flow of the delivery pressure which results in significant falls of efficiency and frequent failures.